Dental handpiece.



No. 831,943. 'PATENTED SEPT. 25, 1906.

' 0. M. FREEMAN.

DENTAL HANDPIEGE. APPLICATION FILED JUNE 5, 1905.

Qua

Zlywentoz UNITED STATES PATENT OFFICE.

DENTAL HANDPIECE.

Specification of Letters Patent.

Patented Sept. 25, 1906.

Application filed June 5, 1905. Serial ITou 263,843.

To all whom it ntay concern.-

Be it known that I, CHESTER M. FREEMAN, a citizen of the United States,residing at Brookline, in the county of Norfolk and State ofMassachusetts, have invented certain new and useful Improvements inDental Handpieces; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to improvements in liandpieces for dentalimplements, and has particular relation to the means employed forsecuring burs or other dental tools to the means employed for operatingsuch tool.

The invention consists in certain novel constructions, combinations, andarrangements of parts, as will be hereinafter more fully described andclaimed.

I11 the accompanying drawings, Figure 1 is a longitudinal sectional viewthrough a dental handpiece constructed in accordance with the presentinvention, portions of the mechanism being shown in side elevation. Fig.2 is a side elevation of the actuating-spindle taken from its casing.Fig. 3 is a detail view of the connecting-thimble for joining thehandpiece to the mechanism which carries it. Fig. 4 is a side elevationof the casing which receives the spindle, the removable end cap notbeing in place thereon. Fig. 5 is a detail view showing the toolgrippingspring. Fig. 6 is a detail sectional view of the removable cap for theend of the handpiece. Fig. 7 is a detail view, in end elevation, of thetool-retaining spring.

In the accompanying drawings I have illustrated a preferred form of myinvention, in which 1 indicates an actuating-spindle, which is inclosedin a non-revoluble casing 2. The spindle finds a bearing in the outercasing at each end thereof, said casing being contracted at its outerend, as shown at 3 in the drawings. The outer end of theactuating-spindle 1 is reduced in size, so as to form an endthrustbearing 4, which engages a corresponding socket-bearing 5, formed in thecontracted portion of the casing. The inner end of the spindle is alsoreduced, as at 6, the reduced portion extending through a bearing 7,formed in a connectingthimble 8. The thimble 8 is provided with threadedend portions, one of which engages internal threads, as at 9, in the endof the casing 2. The other threaded portion ,10, of the thimble isadapted forengagement with the usual flexible connector or tubing whichleads to any suitable power mechanism or engine. The inner end of thereduced spindle portion 6 may also be threaded, as at 11, for connectionwith the power-transmitting member, which is connected with the engineor other source of power. The shoulder 12, formed near the inner end ofthe spindle 1 by the reduction in diameter of the said spindle, abutsagainst the inner end of the thimble 8, the said thimble forming one ofthe end-thrust bearings of the spindle, the other end-thrust bearingbeing formed at 4, as hereinbefore described. The thirnble 8 is formedwith a projecting annular flange 13, which is roughened or serrated uponits outer edge and extends sufficiently beyond the periphery of thecasing 2 to permit the same to be readily grasped by the fingers of theoperator for rotating it when assembling or separating the parts. Theouter end of the spindle 1 is provided with a tool-receiving socket 1 1,which is formed with any suitable means therein for so engaging the tool17 as to prevent rotation thereof within the socketas, for instance, ashoulder 16 is arranged at the inner end of the socket 1 1and the tool17 is formed with a projection or eccentrically-mounted finger 16,adapted to enter the reduced portion of the socket 14, produced by theshoulder 16.

An important feature of this invention is the means by which the bur orother tool 17 is prevented from slipping out of place after it has beeninserted in the socket 1 1. This means preferably consists in a spring18, which is mounted in a groove or recess 19, formed in the contractedend or head portion of the casing 2 and extending longitudinallythereof. The said. spring 18 is secured in position by means of a screw20, which passes through the end of the spring, as at 21, and engagesthe material of the casing-head, as clearly illustrated in Fig. 1. Thespring is free to vibrate except at the end which is secured by the saidscrew 20. The said screw also passes through the removable head-casingor cap 22, so that the end of the screw may be reached from with out thecasing for removal or replacement at any time. By this arrangement alsothe screw 20 is in position to prevent the turning of the cap orhead-casing 22, so that it is locked in place, the said cap beingprovided with internal threads at its inner end 23, which engagecorresponding threads 24, formed upon the reduced portion of the easing2. The outer free end of the spring 18 is preferably turned inwardly atright angles to the body portion thereof, forming a retaining end 25.The bur or other tool 17 is provided with an annular groove 26, which islocated at a proper distance from the end of the bur to reach a pointopposite the end 25 of the spring 18 when the said bur is inserted inthe socket 14. The action of the spring 18 is such that the retainingend portion 25 will normally be sprung into the annular groove 26 andprevent the longitudinal outward movement of the bur or tool.

Although the spring 18 may be positively moved to one side, as will behereinafter described, for permitting of the insertion of the bur ortool, I generally form the retaining end 25 with a beveled portion 27,the bevel being upon the outer surface of said retaining end, so thatwhen the bur or tool is thrust inwardly through the aperture 28 in thecap 22 it will engage the inclined or beveled face 27 and force the endof the spring 18 to one side. As soon as the annular groove 26 arrivesopposite the retaining end 25 said end will be snapped into the saidgroove by the action of the spring.

The tool or bur 17 cannot be withdrawn from its seat in the end of thespindle without first moving the spring 18 to one side and disengagingthe retaining end 25 thereof from the annular groove 26. In order tomake it possible to move the said spring 18 for this purpose, I providethe same at some point intermediate its length with an actuatingprojection 29, which can be reached through an opening or slot 30,formed opposite thereto in the cap 22. The projection 29 is preferablymade in the form of a ring or curved piece, as illustrated in Fig. 7.This ring or curved piece extends from the spring 18, to which it isrigidly attached, around the bored portion of the contracted end 3 ofthe casing 2. An annular groove 31 is formed in the said contracted endof the casing to accommodate the small amount of movement necessary inthe ring 29 for the said ring to vibrate the spring 18 sufficiently topermit the removal of the bur or other dental tool. There is sufficientroom between the cap 22 and the bottom of the groove 19, within whichthe spring 18 is secured, for the said spring to move to a sufficientextent to permit the insertion and removal of the bur or other tool. Thecasing 2 and the spindle 1 terminate at a point just short of theinwardly-turned gripping end of the spring 18. The said end 25 moves inthe space between the end of the spindle and casing and the outerapertured end of the ca 22. The slot 30 in the cap 22 is usuallyeibn-gated transversely of the casing, so that the thumb or finger nailof the operator may readily enter the same for depressing the ring orprojection 29 of the spring 18.

In using the handpiece, when it is desired to insert a bur or otherdental tool in place, it is only necessary to thrust the end thereofthrough the aperture 28 against the inclined or beveled face of theretaining projection 25, forcing the end of the tool past the same andseating it in the socket 14. The end of the spring will snap into theannular groove 26. The bur or tool 17 will thus be held againstlongitudinal movement, and as the engagement of the finger 15 with theshoulder 16 prevents rotation of said tool independently of the spindle1 rotation of said spindle will rotate said bur 2. When the bur is to beremoved, the operator presses upon the proj ection or ring 29, forcingthe free end of the spring 18 toward the inner face of the cap 22. Thisoperates to move the retaining end 25 of the spring far enough to oneside topermit of the withdrawal of the bur or tool.

It will be observed that although the spring 18 is in position topositively lock the bur or other tool from being withdrawn from thehandpiece it has no movement with the spindle, but remains stationarywith the outer casing 2. As above intimated, the mounting of the spring18 is such that the securing setscrew 20 is capable of locking the cap22 is place as well as of holding the spring 18 in its recess or socket.The sole function of the spring 18 is the holding of the bur or toolagainst longitudinal movement, and the spindle 1 is prevented fromengaging or wearing the end of the spring by reason of its mounting inthe outer casing, the endthrust bearings at each end of the enlargedportion of the spindle preventing any longitudinal movement thereof inthe casing 2.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. A dental handpiece, comprising a casing, a rotary spindle arrangedtherein, a longitudinally-removable tool engaging the said spindle, aspring engaging the said casing and also engaging the spindle forpreventing longitudinal movement thereof, a cap threaded onto saidcasing and inclosing said spring and means connecting the spring withthe cap whereby the cap is prevented from rotating by the engagement ofthe spring with the casing.

2. A dental handpiece, comprising a casing, a rotary spindle arrangedtherein, a tool engaging said spindle and longitudinally removabletherefrom, a groove being formed longitudinally in said casing, a springlying within the longitudinal groove and formed with means engaging saidtool for normally preventing longitudinal movement thereof, a capthreaded onto said casing inclosing said spring, and connections betweenthe spring and cap for preventing rotation of the cap independently ofthe casing.

3. A dental handpiece, comprising a casing, a spindle mounted thereinand formed with a tool-supporting socket, a tool extending into saidsocket, a spring for locking the tool in the socket and means forrigidly se curing one end of the spring to the casing.

4. A dental handpiece, comprising a spindle having a tool-carryingsocket formed therein, a tool extending into said socket and formedintermediate its length with an annular depression, a casing inclosingthe spindle and producing thrust-bearings therefor, a spring securedrigidly to said casing at one end and at its free end extending oppositethe annular depression in the tool for retaining the tool normallyagainst longitudinal movement.

5. A dental handpiece, comprising a toolcarrying spindle, a casing forinclosing the same, a tool engaging said spindle, a lockingspringrigidly secured to the casing at one end, having its free end turnedinwardly to engage said tool for retaining the same in place, and meansprojecting beyond the casing for moving the spring to one side for releasing the tool.

6. A dental handpiece, comprising a spindle, a casing inclosing thesame, a tool carried by said spindle, a spring secured to the casing atone side of the spindle and engaging the tool for normally retaining thesame in place, and means projecting from the spring and encircling thespindle-casing and extending beyond the spindle on the opposite 'sidefrom the spring for releasing the spindle from its engagement with thetool.

7. A dental handpiece, comprising a spindle having a reduced,tool-carrying, socketed end, an annularlygrooved tool arranged therein,a casing forming bearings for the spindle and inclosing the same, saidcasing having a recess to receive the locking-spring, a locking-springarranged therein and having an enlarged end, a screw securingsaidenlarged end within said casing, the free end of the spring having aninturned, beveled end adapted to engage the groove of the tool fornormally retaining the same in the socket of said spindle, and meansprojecting from the spring and extending on the opposite side of thespindle for moving the spring to one side for facilitating release ofthe tool.

8. A dental handpiece comprising a casing having a head portion formedwith an internal bearing, a spindle extending through said bearing, aspring mounted in the head, a projection for moving the spring, saidprojection surrounding the spindle-bearing and extending to the oppositeside of the head from the spring, a cap fitting upon the head andprovided with a slot opposite the said projection and a set-screw forholding the spring in place, the said set-screw also locking the cap inposition.

9. A dental handpiece comprising a casing having a spindle-bearingformed therein, a spindle mounted in the casing and engaging the saidbearing, a tool gripping spring mounted in the casing and a ring formedupon the spring for vibrating the same, the said ring extending aroundthe bearing and the spindle so that by pressing upon the ring the springmay move away from the spindle.

In testimony whereof I affix my signature in presence of two witnesses.

CHESTER M. FREEMAN.

Witnesses:

S. FRASER, S. L. RIDEoU'r.

